Safety in a double pack at 10 meters depth in Berlin-Frohnau

It was an excavation pit protection with record-breaking dimensions - this was all building partners involved in the sewer rehabilitation project in Berlin-Frohnau agree. Carl Zauber Tiefbau GmbH had initially been commissioned by the Reinickendorf Civil Engineering Office to secure a so-called sinking point in the forest settlement characterized by individual buildings and villas. The subsequent camera inspection of the wastewater sewer and the damage patterns determined in the process then resulted in the follow-up order from Berliner Wasserbetriebe for the rehabilitation of the affected sewer section.

After examining various alternatives, the company used the e+s linear shoring system from thyssenkrupp Infrastructure to secure the construction work on the pipeline, which is up to 10 meters deep. Particularly noteworthy is the fact that two linear shoring units were coupled together to secure the excavation pit. This was done while ensuring the enormous depths achievable with this method required load transfer.

The loss was preceded by a rainfall event of the century, which occurred at the end of June 2017 in large parts of Berlin with crowded cellars, flooded streets and waterfalls in subway stations for a two-day state of emergency in of the capital. Causes like these ultimately caused the paved road surface to subside.

Sustainable concept developed

In this phase, the company became aware of linear shoring and found a competent partner in thyssenkrupp Infrastrucure to develop a viable concept for securing a construction pit at this depth. The construction partners took advantage of this to secure the excavation pit in Berlin-Frohnau by using so-called deep linear shoring.

The deep linear shoring, in which two shoring units are connected with each other, combines the advantages of the linear shoring system into a powerful functional principle that was virtually ideal for the sewer construction project due to the general conditions. Differently than with the conventional linear shoring the first module, which is brought into the soil, consists of doubled carrier pairs, which are connected at the upper end with a tension adapter with one another.

In the excavation pit secured in this way, the damaged pipes could be replaced and a manhole can be renewed before the excavation pit is filled with water while at the same pulling the shoring elements was successively backfilled.